I know the Nacra 6.0 does have a nutplate inside the beam for these dolphin striker bolts. I would imagine that the Mystere does too (you should be able to see it from the end of the beam).

You CAN anodize aluminum after removing the paint - however, chances are that it will not have a very consistent appearance. Any imperfection, bit of corrosion, or the tiniest of paint spec will leave a much larger mark in the anodizing coating. It will, however, have great future corrosion resistance as expected from an anodized component.